Abstract

Using the concept of spin filter tunneling, we propose a scheme to turn on and off the spin polarization of a transport current. This is achievable in a double spin filter tunneling geometry, where the net spin polarization of the transient current can be switched off when the two spin filters are aligned antiparallel to each other such that their filtering effects cancel out. When aligned parallel, the two spin filters strengthen each other and the transient current is thus highly spin polarized. This magnetic manipulation gives an additional degree of freedom to tune or even turn off a transport current’s spin polarization. We also show that, to some extent, the degree of spin polarization can be linearly varied with an applied bias voltage.